Nitrous oxide (N2O) is used as an inhalative gas during anesthesia, labour and at some dentist practices, most frequent in a fixed 50:50 combination with O2. N2O has a strong analgetic effect, and none or only slight sedative effects in concentrations < 80%. N2O has a very rapid onset of effect (a few seconds), and its half-life in the human body after the stop of inhalation is shorter than 1 minute (3). Patients receiving N2O in a 50:50 combination with O2 are awake, don't need post-procedure recovery and may drive their own car home (4). However, as N2O diffuses quickly through biological membranes, caution is warranted when used for patients with the following conditions: sinusitis, otitis, ileus, bowl obstruction, and megacolon. Pregnant women should not be exposed to N2O.